The invention relates to a compressed-gas cutout, especially for high voltage, with a fixed contact element and a movable contact element interacting with the latter, a drive rod connecting the movable contact element with a drive, and a disconnecting braking structure for braking the disconnecting movement of the drive rod, as well as a disconnecting braking structure for a compressed-gas cutout, especially for high voltage.
A compressed-gas cutout of this type is known from European patent application no. 95120347.0. It refers to a so-called blast piston switch, where a blast piston moves with a blast cylinder in the final phase of a disconnecting action. Whereas in the case of compressed-gas cutouts with fixed blast pistons, towards the end of the disconnecting stroke the residual gas in the piston-cylinder-system forms a gas cushion that supports the braking of the moved masses, the residual gas cannot be used for braking the moved masses in blast piston switches. Thus, a pneumatic disconnecting arrangement is used for the compressed-gas cutout pursuant to European patent application no. 95120347.0. The disconnecting braking arrangement contains a braking piston that is loosely arranged on the drive rod and that is entrained by a stop in the end section. These brakes have a low overall height and they are therefore well suited for installation in the limited space that is available in the switch chamber. They have the disadvantage that they have to be produced with particularly narrow tolerances and that the energy that is converted into heat during the braking action is no longer available for a following connecting action.
The use of a hydraulic brake for a compressed-gas cutout is known from DE-C-32 15 243. Due to the high viscosity of the flow medium, the demands regarding the tolerances during production of a hydraulic brake are less than those for a pneumatic brake. This solution, however, has the disadvantage that not only the insulating gas but another medium has to be monitored, namely the hydraulic fluid, and above all, this monitoring takes place in a location that is difficult to access. In the case of a hydraulic brake, the brake energy is also lost after the disconnecting action.
Finally, from DE-A 41 16 314 a brake is known that is based on friction. This brake is also not suitable for a compressed-gas cutout, because friction results in abrasion, i.e., fine, possibly metallic powder that can adversely affect the insulation capability of the insulating gas. Furthermore, as with pneumatic and hydraulic brakes, the brake energy is lost after a disconnecting action.